golfinz

I've noticed this past weekend that the T4R is acting funny while on the highway. I've included a video of the rpm gauge to illustrate what I'm seeing/whats happening - it happens at the :16 and :21 second mark.



The typical scenario is this: I'm cruising on the highway, holding the car at a constant speed (ie: not accelerating or not decelerating) and the rpms will start to dip and bounce like it does in the video at the 16 and 21 second mark. When this happens, the car will slow down as the rpms dip and if I try to accelerate, the gas pedal feels mushy/like I'm trying to push the pedal through peanut butter (ie: I can press it down but it is very hard to do so). While this is happening, the car does not react to the additional pressing of the accelerator. After a few seconds, it will 'kick in' and the rpms will jump up and the car will start accelerating again as I gain control over the gas pedal. This typically happens right at the 1800-2200 rpm mark and does not happen when I am accelerating or below/above this rpm range.

The check engine light is not on nor is it so bad that it truly interferes with the trucks ability to drive; hell, I drove 1200 miles this weekend alone without missing a beat. I would like to try to figure this out before anything serious happens. Its a 2002 limited, 4wd with 171k miles on it

golfinz

I'm thinking this isn't an injector or plug related issue because if those were the culprit, this issue would be seen at other rpm's/speed/etc

Old_ blue

Clean your throttle body and maf. Then check your tps if it has any "drop outs" like it will keep increasing in voltage then dip in voltage in a certain spot. also check throttle linkage.

golfinz

Ill start with cleaning the tb and maf. To check the tps voltage, I'll need to buy a obdii reader, correct?

Old_ blue

no a digital multi meter. u could use a scanner as well though

golfinz

I went by Autozone to have the codes pulled and a P0420 came up. Can this code come up without a SES, because I don't have an SES light on.

I did replace my rear 02 sensor in January because of this code but at that time, I did have the SES light on. When I replaced the sensor, the light went away and it hasn't come back on since.

Old_ blue

ya 420 i think is a 2 trip code. it takes 2 trips to set code/check engine light. ya definitely check your o2 sensor out thats what the code is for. look in a service manual if its for low reference or biased lean cuz it could be that meaning the sensor itself is having trouble.

golfinz

Damn it! I don't have a service manual to figure out if it's working properly/within spec. Need to see if I can find one online

golfinz

Just to update, I got rid of the hesitation by cleaning the maf and TB

golfinz

I cleaned them both back in May/June and it hasn't happened since and I've put about 6k miles on the truck since then